The world's central banks can't ignore the growth in cryptocurrencies and may at some point have to consider whether it makes sense for them to issue their own digital currencies, according to the Bank for International Settlements.

... with bitcoin and others gaining in popularity as payment systems go mobile and investors pour in money, central banks are beginning to delve into them and their underlying blockchain technology, which promises to speed up clearing and settlements. At the Bank of England, Mark Carney has cited cryptocurrencies as part of a potential "revolution" in finance.